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PubMed2002

Stable social aggregations in an Australian lizard, Egernia stokesii.

Social groups in many animal species contain family members, and are maintained by parental care, and then tolerance of related individuals in the group. Lizards rarely show prolonged parental care, and rarely form stable social aggregations, although cohesive groups have been reported in the Australian skink genus, Egernia. A population of Egernia stokesii was surveyed for six seasons on Camel Hill, South Australia. At this site individuals occupied rock crevices for refuges on an isolated rocky outcrop of about 1.5 ha. The population was divided into 17 stable social groups, each containing 2-17 individual lizards. Surveyed juveniles took more than 5 years to reach mature size, and most juveniles and subadults remained in the social group of their parents for that period and longer. There were 2-8 permanent adult members of each group. Group members shared common crevice refuges, basked close together (and sometimes on top of each other) and defecated in common scat piles. There was low mortality after the first 2 years of life, and low dispersal either into or out of the population. Some individuals were "floaters" that did not belong to a social group. Over the study a number of these became established in groups. The social structure of these lizards resembles the family groups reported in many species of birds and mammals where group members help to raise the offspring of relatives. The low level of parental care in lizards suggests that the evolution of this form of social organisation in lizards has resulted from different processes than in other vertebrate taxa.

Aging↗
PubMed2005

Sexually selected signals are not similar to sports handicaps.

The handicap principle is a simple but powerful metaphor that has had a major impact on how biologists study and understand sexual selection. Here, I show that its application to signalling in sexual selection is not a valid generalization from its roots in economics. Although some signalling systems, with additive costs and benefits, have solutions that resemble sports handicaps, the signalling in sexual selection has multiplicative costs and benefits, and solutions that do not resemble sports handicaps. The sports analogy is technically incorrect, metaphorically misleading and a poor guide for empirical research on the signalling in sexual selection. The evolution of sexually selected signals is not a missing piece of Darwin's puzzle; it is an integral piece of the process of evolution by natural selection, and it should be approached with the same tools that we bring to bear on the evolution of other correlated traits involved in social interactions.

Animal Communication↗
PubMed2005

Genes, brains and mammalian social bonds.

Recent studies of monogamous species have revealed the role of the neuropeptides oxytocin and vasopressin in activating reward mechanisms of the brain that are involved in establishing partner recognition and selective 'bonding'. The evolutionary history of these findings resides, at a mechanistic level, in the reciprocal bonding between mother and infant that is common to all mammals. However, in Old World primates, where mother and infant alone would not survive, living in large social groups brings extended family relationships and provides for alloparenting. This has required the emancipation of parenting behaviour from the constraints of hormonal state and the evolution of large brains for decision making that was previously restricted and determined by hormonal state. How this has been achieved, what conserved mechanisms underpin social bonding, and what genetic and mechanistic changes have occurred in the evolution of social bonds are the issues addressed here.

Journal Article↗
PubMed2004

Duplication and diversifying selection among termite antifungal peptides.

We have identified and analyzed the mRNA sequence of 20 new defensin-like peptides from 11 Australian termite species of Nasutitermes and from an outgroup, Drepanotermes rubriceps. The sequence was amplified by reverse transcriptase PCR with a degenerate primer designed from termicin, an antifungal peptide previously characterized from the termite Pseudocanthotermes spiniger. All 20 genes show high sequence identity with P. spiniger termicin and have duplicated repeatedly during the radiation of Nasutitermes. Comparison of the relative fixation rates of synonymous (silent) and nonsynonymous (amino acid altering) mutations indicates that the Nasutitermes termicins are positively selected. This positive selection appears to drive a decrease in termicin charge. In termites with two genes, the decrease in charge is predominantly restricted to one termicin. Furthermore, the spread of charge is significantly greater within species than across species among amino acid sites that appear to be under strong positive selection and this spread is attributable to only three sites. Our results suggest that after termicin duplication, certain critical sites have maintained a positive charge in one duplicate and evolved towards neutrality in the other and that positive selection has directed these changes repeatedly and independently. This diversification among duplicated genes may be a counter-response to the evolution of fungal resistance in social insects that are particularly vulnerable to fungal epidemics.

Amino Acid Sequence↗
PubMed1981

[Delinquency and drugs in the Juvenile Court of Vaud canton-from 1971 to 1979].

The evolution of illicit drug consumption by adolescents in the canton of Vaud, 1971 to 1979, was assessed from data available by the Juvenile Court. Some results of this study are presented. The quantitative changes are then discussed in relation with changes in the social framework, such as the evolution of the ideology of delinquent adolescents, the altered concepts of repression by the police and jurisdiction, and the evolution of facilities for the care of drug users.

Adolescent↗
PubMed1998

Knowledge acquired and decisions made: triadic interactions during allogrooming in wild bonnet macaques, Macaca radiata.

The pressures of developing and maintaining intricate social relationships may have led to the evolution of enhanced cognitive abilities in many nonhuman primates. Knowledge of the dominance ranks and social relationships of other individuals, in particular, is important in evaluating one's position in the rank hierarchy and affiliative networks. Triadic interactions offer an excellent opportunity to examine whether decisions are taken by individuals on the basis of such knowledge. Allogrooming supplants among wild female bonnet macaques (macaca radiata) usually involved the subordinate female of a grooming dyad retreating at the approach of a female dominant to both members of the dyad. In a few exceptional cases, however, the dominant member of the dyad retreated; simple non-cognitive hypotheses involving dyadic rank differences and agonistic relationships failed to explain this phenomenon. Instead, retreat by the dominant individual was positively correlated with the social attractiveness of her subordinate companion (as measured by the duration of grooming received by the latter from other females in the troop). This suggests that not only does an individual evaluate relationships among other females, but does so on the basis of the amount of grooming received by them. Similarly, the frequency of approaches received by any female was correlated with her social attractiveness when she was the dominant member of the dyad, but not when she was the subordinate. This indicated that approaching females might be aware of the relative dominance ranks of the two allogrooming individuals. In logistic regression analyses, the probability of any individual retreating was found to be influenced more by her knowledge of her rank difference with both the other interactants, rather than by their absolute ranks. Moreover, information about social attractiveness appeared to be used in terms of correlated dominance ranks. The nature of knowledge acquired by bonnet macaque females may thus be egotistical in that other individuals are evaluated relative to oneself, integrative in that information about all other interactants is used simultaneously, and hierarchical in the ability to preferentially use certain categories of knowledge for the storage of related information from other domains.

Aggression↗
PubMed2003

Diversification of Sulawesi macaque monkeys: decoupled evolution of mitochondrial and autosomal DNA.

In macaque monkeys, females are philopatric and males are obligate dispersers. This social system is expected to differently affect evolution of genetic elements depending on their mode of inheritance. Because of this, the geographic structure of molecular variation may differ considerably in mitochondrial DNA (mtDNA) and in autosomal DNA (aDNA) in the same individuals, even though these genomes are partially co-inherited. On the Indonesian island of Sulawesi, macaque monkeys underwent an explosive diversification as a result of range fragmentation. Today, barriers to dispersal have receded and fertile hybrid individuals can be found at contact zones between parapatric species. In this study, we examine the impact of range fragmentation on Sulawesi macaque mtDNA and aDNA by comparing evolution, phylogeography, and population subdivision of each genome. Our results suggest that mtDNA is paraphyletic in some species, and that mtDNA phylogeography is largely consistent with a pattern of isolation by distance. Autosomal DNA, however, is suggestive of fragmentation, in that interspecific differentiation across most contact zones is significant but intraspecific differentiation between contact zones is not. Furthermore, in mtDNA, most molecular variation is partitioned between populations within species but in aDNA most variation is partitioned within populations. That mtDNA has a different geographic structure than aDNA (and morphology) in these primates is a probable consequence of (1) a high level of ancestral polymorphism in mtDNA, (2) differences between patterns of ancestral dispersal of matrilines and contemporary dispersal of males, and (3) the fact that female philopatry impedes gene flow of macaque mtDNA.

Alleles↗
PubMed1975

[Classification of mental phenomena as the highest integration level of man's relationship to the environment (with remarks on the phenomenon of altered states of consciousness)].

In recent years mystical ideas have been spreading concerning "altered states of consciousness" as "new dimensions of experience and transpersonal communication". An analysis is given of the class-conditioned character of these concepts deriving from the insecure social conditions existing under moribund imperialism. This is contrasted with the dialectical materialist concept of psychic phenomena as the highest integration level of man's relationship to the environment. Psychic phenomena are interpreted not as epiphenomena but as an expression of the new quality attained in the evolution of man as a social being in the central control of all functions of man's organism.

Brain↗
PubMed2000

Sex-specific predation on a monogamous rat, Hypogeomys antimena (Muridae: Nesomyinae).

Sex-specific predation on adult individuals is often predicted by different behaviour in males and females resulting from different reproductive strategies and social systems. High predation pressure and the need for biparental care are considered a possible ecological basis for the evolution of monogamy, the most puzzling social system in mammals. In species where adults and offspring are vulnerable to the same predators, males and females may protect their offspring to different extents because of conflicting demands of investment in current and future offspring. I present the first empirical data on age- and sex-specific predation pressure by top predators on a monogamous rodent and the sex-specific behavioural responses of the prey species to different rates of predation. During an annual predation peak, only offspring and adult males were killed but no females. Whereas males and females travelled similar distances at night before the period of high predation on offspring, males moved further during this period. At the same time, males and females increased their distance from their offspring but males stayed closer to them than females. As a consequence, the distance between the members of the pair increased during the predation peak. The males' behaviour could lead to their encountering predators more frequently which would reduce survival prospects. The different behaviour of males and females provides empirical evidence that males invest in the welfare of current offspring at the cost of higher predation risk whereas females protect their residual reproductive value. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2000

[Do medical schools still train doctors?].

In practice, medical finals are not final and a supplementary training is necessary before medicine may be practised independently. Social factors and an ongoing evolution of medical science prompt reconsideration of the structure, content and duration of the training of doctors and specialists. This was the subject of a meeting of this Journal. One possibility of differentiation in the basic training is an early subdivision into care physicians, clinical specialists and health physicians. In the training of social medical officers one of the factors to be taken into account is the influence of principals. For GP's, postgraduate training is increasingly important because of social and other developments. The training of non-surgical specialists can be made shorter since a significant proportion of the time in the present training is devoted to areas requiring special attention. The training of surgical specialists could be shortened by introducing a training programme that is independent of the procedure. Responsibility for the total care of the patient will be borne by the specialists jointly.

Education, Continuing↗
PubMed2006

Parochial altruism in humans.

Social norms and the associated altruistic behaviours are decisive for the evolution of human cooperation and the maintenance of social order, and they affect family life, politics and economic interactions. However, as altruistic norm compliance and norm enforcement often emerge in the context of inter-group conflicts, they are likely to be shaped by parochialism--a preference for favouring the members of one's ethnic, racial or language group. We have conducted punishment experiments, which allow 'impartial' observers to punish norm violators, with indigenous groups in Papua New Guinea. Here we show that these experiments confirm the prediction of parochialism. We found that punishers protect ingroup victims--who suffer from a norm violation--much more than they do outgroup victims, regardless of the norm violator's group affiliation. Norm violators also expect that punishers will be lenient if the latter belong to their social group. As a consequence, norm violations occur more often if the punisher and the norm violator belong to the same group. Our results are puzzling for evolutionary multi-level selection theories based on selective group extinction as well as for theories of individual selection; they also indicate the need to explicitly examine the interactions between individuals stemming from different groups in evolutionary models.

Adolescent↗
PubMed1998

Social capital and health: implications for public health and epidemiology.

Public health and its "basic science", epidemiology, have become colonised by the individualistic ethic of medicine and economics. Despite a history in public health dating back to John Snow that underlined the importance of social systems for health, an imbalance has developed in the attention given to generating "social capital" compared to such things as modification of individual's risk factors. In an illustrative analysis comparing the potential of six progressively less individualised and more community-focused interventions to prevent deaths from heart disease, social support and measures to increase social cohesion faired well against more individual medical care approaches. In the face of such evidence public health professionals and epidemiologists have an ethical and strategic decision concerning the relative effort they give to increasing social cohesion in communities vs expanding access for individuals to traditional public health programs. Practitioners' relative efforts will be influenced by the kind of research that is being produced by epidemiologists and by the political climate of acceptability for voluntary individual "treatment" approaches vs universal policies to build "social capital". For epidemiologists to further our emerging understanding of the link between social capital and health they must confront issues in measurement, study design and analysis. For public health advocates to sensitise the political environment to the potential dividend from building social capital, they must confront the values that focus on individual-level causal models rather than models of social structure (dis)integration. The evolution of explanations for inequalities in health is used to illustrate the nature of the change in values.

Causality↗
PubMed1988

Hereditary essential tremor in Buenos Aires (Argentina).

A descriptive trial of essential tremor in Buenos Aires city is proposed. It may be considered as the first one like this in Latin America. During a 15 year period, sixteen families with essential tremor diagnosis have been examined, making a total of 39 patients (20 males and 19 females). The disease was basically studied from its semiological, clinico-evolutive and therapeutical view point, following a protocol. Our results indicate -- a. The clinico-evolutive characteristics: its frequency (according to race, sex, social status, age of beginning and physiopathological type), morbidity and mortality, evolution, prognosis, triggering factors, longevity and multiparity. b. The different treatment given to our patients with discussion of their pharmacokinetic and pharmacodynamic basis and evaluation of the best responses. In this matter, it is concluded that both primidone (750 mg/daily) and/or propranolol (160-240 mg/daily) are undeniably the drugs of first choice for the treatment of this disease. A comparison of the clinico-therapeutic features of this tremor in Buenos Aires and other cities is done. The study of this syndrome in Buenos Aires does not give different results from those obtained in Europe and USA.

Argentina↗
PubMed1997

Species differences in V1a receptor gene expression in monogamous and nonmonogamous voles: behavioral consequences.

Arginine vasopressin modulates a number of species-typical social behaviors, including social memory in rats, scent marking and aggressive behavior in hamsters, and partner preference formation and paternal behavior in monogamous rodents. The distribution of V1a receptor binding sites in the brain varies greatly among species. Using in situ hybridization in 2 species of voles with strikingly different patterns of V1a binding sites and social behaviors, the authors demonstrate that differences in V1a receptor binding sites are due to species differences in regional V1a receptor gene expression. It is then demonstrated that the differences in receptor gene expression are associated with species differences in behavioral response to centrally administered vasopressin. Together, these data suggest that the phylogenetic plasticity of central neurohypophyseal peptide receptor expression may contribute to the evolution of species-typical social behaviors.

Amino Acid Sequence↗
PubMed1992

Continuity and change revisited.

This concluding article summarizes key points about continuity and change in gerontology as described in the four previous articles. Synthesis and discussion is focused on five major areas in which gerontological continuity and change are evidenced: 1) transformation of basic themes over time; 2) gerontology's identity crisis; 3) the social ideology of gerontology; 4) evolution and refinement of gerontological ideas and methods; and 5) temporal frameworks. The author raises questions about unsolved issues and suggests the eventual need to examine the roles of individuals in shaping the field of study called gerontology.

Aging↗
PubMedDate not supplied

Biological adaptation and social behaviour.

In 1930, both Fisher and Wright identified Darwin's initial concept of adaptive evolution in the light of the genetical theory with intergenerational variation in allelic frequencies brought about by the action of natural selection through differential reproduction. They emphasized that selection only works at the level of the individual and that its only consequence is to increase fitness. One genetical evolution not easy to explain on these bases was that of social behaviour because any altruistic gene disadvantageous for its carriers in an antisocial environment would have been opposed by selection. In the 1950s, ethologists focusing on what appeared to be evolved collective behaviours, hypothesized that selection could operate at group level. Though the controversy between group selectionists and evolutionary geneticists ended by the rejection of the evolutionary role of group selection, it has remained a subject of investigation until now. Kin selection, proposed by Hamilton, offered a solution to the problem of the evolution of altruism and gave the impetus to the trend of adaptive explanations of basic behaviours, which was to become the core of human sociobiology. The intrusion of behaviour into the process of adaptive evolution was an invitation to investigate culture as an evolutive process. The first sociobiological interpretations of culture as a derivative of genetic processes were followed by other ideas in which culture, though channelled by evolved predispositions, was essentially free from biological determinism. It is concluded that as we have come to better understand human adaptation, its complexities have been further revealed, a development already implicit in Darwin's notion.

Adaptation, Physiological↗
PubMed1994

[The psychological meaning of the female friend among Mexican adolescents: a gender comparison].

This study constitutes a continuation of a series of approximation to the knowledge of an adolescent stage. The purpose of this paper is to explore the way in that the females and males adolescents conceptualize a "female friend". With this in mind, we analyzed the information with the semantic network technique in 160 adolescents: 80 females and 80 males divided in two groups of analysis: 8th and 12th school years in private schools from Mexico City. The results permit to observe some differences in their conceptualizations by gender and educative level; but also we observed similarities in the way of to conceptualize a "female friend". Perhaps these findings derived from a cultural tradition that influence the social interactions and by an evolutive stage: the adolescence, when the establishment of the psychosocial identity is an important need and demand.

Adolescent↗